import java.util.Stack;

public class MyQueue {
    Stack<Integer> stack1;
    Stack<Integer> stack2;

    public MyQueue() {
        stack1 = new Stack<>();
        stack2 = new Stack<>();
    }

    public void push(int x) {
        stack1.push(x);
    }

    public int pop() {
        if (stack2.isEmpty()) {
            int curSize = stack1.size();
            for (int i = 0; i < curSize; i++) {
                int x = stack1.pop();
                stack2.push(x);
            }
        }
        if (stack2.isEmpty()) {
            return -1;
        }
        return stack2.pop();
    }

    public int peek() {
        if (stack2.isEmpty()) {
            int curSize = stack1.size();
            for (int i = 0; i < curSize; i++) {
                int x = stack1.pop();
                stack2.push(x);
            }
        }
        if (stack2.isEmpty()) {
            return -1;
        }
        return stack2.peek();
    }

    public boolean empty() {
        return stack1.isEmpty() && stack2.isEmpty();
    }
}